During the Mexican War Ford was adjutant of Hays's regiment and in command of a spy company; he was commended for gallant service by Gen. Joseph Lane. Out of all the many accomplishments that John Salmon Ford would be remembered for, the most prominant would be the lasting nickname "RIP". While serving as adjutant, While serving as adjutant, Ford acquired the lasting nickname "Rip." When officially sending out notices of deaths he kindly included at the first of the message, "Rest in Peace"; later, under the exigencies of battle conditions, this message was shortened to "R.I.P." it was Ford’s unpleasant duty to write to the deceased soldier’s loved ones that he had died. Because of the large number of deaths from diseases such as Yellow Fever, Ford soon found the volume of letters he was having to write so vast that he shortened the closing to "Rest In Peace," which he later shortened even more to "RIP." Forever after, Ford would no longer be John Ford—he would be known as Rip Ford and in later life, Old Rip.

In 1849, with Robert S. Neighbors, Ford made an exploration of the country between San Antonio and El Paso and published a report and map of the route, which came to be known as the Ford and Neighbors Trail. Later in 1849 he was made captain in the Texas Rangers and was stationed between the Nueces and the Rio Grande, where he had numerous Indian fights during 1850 and 1851.

In 1852 he was elected to the Texas Senate; again he became an editor and, in partnership with Capt. Joe Walker, established the State Times, which was published in Austin until 1857. Early in 1858 he accepted a commission in the state troops and defeated the Indians in two major battles on the Canadian River. Late in 1859 he was sent to the Rio Grande, where he commanded operations against Juan N. Cortina. In 1861 Ford served as a member of the Secession Convention, commanded an expedition to Brazos Santiago, initiated a trade agreement between Mexico and the Confederacy, and was elected colonel of the Second Texas Cavalry, with a command in the Rio Grande district. Between 1862 and 1865 he was engaged on border operations protecting Confederate-Mexican trade. On May 13, 1865, Confederate forces under the command of Rip Ford defeated Union forces at the Battle of Palmito Ranch, the last battle of the Civil War.

In 1868 Ford moved to Brownsville to edit the Brownsville Sentinel. In 1872 he was a delegate to the Democratic convention in Baltimore. He was a special sergeant-at-arms when Richard Coke was inaugurated as governor in 1873 and quelled a riot of Austin citizens who were aroused against the radicals and Edmund J. Davis. In 1873 Ford served as a cattle and hide inspector of Cameron County, and in 1874 he was mayor of Brownsville. He was a member of the Constitutional Convention of 1875 and served in the Texas Senate from 1876 to 1879, when he was appointed superintendent of the Deaf and Dumb School (later the Texas School for the Deaf).

Ford spent his later years writing reminiscences and historical articles and promoting an interest in Texas history. As a charter member of the Texas State Historical Association, he contributed one of the first articles published in its Quarterly. He died in San Antonio on November 3, 1897 and is buried in the Confederate Cemetery there.